Solve for x in the following equation:

 $\frac{1}{4}x+\frac{2}{7}x\ =\ 15$  

 $\left(7x-14\right)^2=-7$  

How many solutions are there for the following quadratic equation:

What method is being applied in the following example:


If $5+\left(x-4\right)=15$  then  $\left(x-4\right)\ must\ equal\ 10$